1. Field of the Invention
The present embodiments relate to devices and methods of sample preparation for imaging systems. More specifically, the present embodiments relate to a sample preparation stage having multiple degrees of freedom allowing for in situ sample preparation and imaging.
2. Description of the Related Art
Samples for electron microscope imaging require certain preparation for observation under transmitted light or electron radiation. For example, thin slices (or sections) of a sample are typically cut or milled from a bulk sample in a grid or tube. The cutting or milling can be performed by a focused ion beam (FIB) system, or within a dual beam system that includes both a FIB and an electron microscope. Examples of such dual beam systems include the Quanta 3D DualBeam systems from FEI Corporation (Hillsboro, Oreg., USA). However, after the thin slices are prepared using the FIB, the samples must then be transferred to a platform suitable for imaging. Microscopic imaging, such as scanning transmission electron microscope (STEM), can require positioning along multiple degrees of freedom in order to capture a proper image.
Others have prepared stages for STEM imaging that have multiple degrees of freedom. For example, U.S. Pat. No. 7,474,419 describes a stage assembly for positioning a sample in the vicinity of a reference point. The stage assembly includes a sample table to which the sample can be mounted and a set of actuators arranged so as to effect translation of the sample table along directions substantially parallel to an X-axis perpendicular to a reference plane, a Y-axis parallel to the reference plane, and a Z-axis parallel to the reference plane. The X-axis, Y-axis and Z-axis are mutually orthogonal and passing through the reference point. In addition, U.S. Pat. No. 6,963,068 describes a manipulator that has a table that can be moved in five degrees of freedom, with three perpendicular translations and two rotations.
However, techniques for manipulating samples for STEM or TEM analysis are more complex, and can require manipulating samples for both FIB milling and carving and the later STEM analysis to be performed at specific, critical temperature to prevent ice crystal formation in the sample, or undesirable thawing of the sample between manipulations. Thus, what is needed is a system that allows for complex manipulations of samples for STEM or TEM imaging without the requiring so much sample handling that the sample becomes destroyed.